This “people detector” with pyroelectric sensor was found in the April 1991 issue of Radio Electronics magazine. The circuit is based on an LM324 and a sensor from that time.
Found in an English documentation from 1989, this circuit uses components common today. The...
The LED frequency flashes depends on the value of the capacitor tested according to the table. We...
Found in a Popular Electronics from the 90s, this circuit generates a signal that depends on the...